375 Cheytac brass length differences with Peterson brass. Neck splitting after three firings.

[Robinireland]

Hi from the United Kingdom.

With ELR components being about as rare as tits on a snake here in the U.K., I have two lots of Peterson brass for my Voere X5 in 375 Cheytac. The rifle was bought and built in 2020 and shipped directly from the factory.

My problem is that both batches of brass vary in length by over 10 thou. One lot shows a consistent length of 3.020”, whilst the other shows an equally consistent 3.034”. Both feed and function fine.

The longer brass came pre primed from an ammunition manufacturer (to various Armed Forces), whereas the shorter brass came in 50 count retail boxes, bought from a U.K. retailer whilst we still had such items in our shops.

Any ideas as to why there appears to be such a difference in what should, in my view, be identical brass?

I’ve only just begun testing loads with Lehigh Defence 353gr Match Solids with Reloader 50 and have worked up to 142.5gr
which are producing 3,100fps from a 36” barrel with 1 in 10” twist, from both types of brass.

And here’s my second question; how many firings should I expect from Peterson brass?
With the aforementioned load I’m getting no signs of pressure, primers look good (ie not flat, but beginning to fill out the pocket), no ejector marks on case head. Bolt lift is heavy on the Voere X5 (it’s a huge bolt. Even on an empty chamber it needs a strong lift).
But, I’m only managing three firings before necks are splitting.

Should I be annealing after every firing?

I full size my brass with a CH4D die (it’s difficult to find anything in the U.K., so I’m somewhat limited to choice.

Fire forming all my brass is out of the question, as barrel life and availability of new barrels make this an uneconomical option.

Any constructive and informative comments and advice will be gratefully accepted, but please bear in mind this is from a U.K. shooter where, as mentioned, ELR calibres such as 375, 408, 416 and all the variations are still quite rare, so it’s likely (to me) that what may be common knowledge in the USA and other matured ELR countries may not be so readily available here.

Thank you for taking the time to read this.

 

[spife7980]

But, I’m only managing three firings before necks are splitting.

Should I be annealing after every firing?

Fire forming all my brass is out of the question, as barrel life and availability of new barrels make this an uneconomical option.

Then choose one lot, long or short, and use those only then.
I dont know anything about the cheytac chamber dimensions but I would figure out how long the chamber is and let that tell you if you need to trim one back or what. Maybe the manufacturer will give you a reamer print. Or you could chamber a piece of brass and use a bore scope down the muzzle to see if the long is too long. Or you could buy a snalcair chamber length gauge and hopefully theyll ship it overseas.
I doubt the load you come up with would change based on that case length alone.

 

[Taylorbok]

.375 Cheytac brass vs reamer base dimension

Peterson brass measures .633 at the .200" mark at the base and my reamer is about .6395 at the .200" mark. There seams to be different specs on the Cheytac all over the place. Is this .0065 bigger base going to cause issues with brass expanding that much at the base? What are you guys using...

www.snipershide.com

IMO you should have no problem fire forming that brass and then just push the shoulder back .002 from where it forms and call it good.

 

[Robinireland]

Then choose one lot, long or short, and use those only then.
I dont know anything about the cheytac chamber dimensions but I would figure out how long the chamber is and let that tell you if you need to trim one back or what. Maybe the manufacturer will give you a reamer print. Or you could chamber a piece of brass and use a bore scope down the muzzle to see if the long is too long. Or you could buy a snalcair chamber length gauge and hopefully theyll ship it overseas.
I doubt the load you come up with would change based on that case length alone.

Thank you.
That sounds like a good starting point.

I’ll mail Voere and ask them for dimensions as well as expected brass length in relation to the chamber.

Naturally I’d prefer the shorter brass to be the correct fit, as I can shorten the milspec brass to suit.

 

[spife7980]

Naturally I’d prefer the shorter brass to be the correct fit, as I can shorten the milspec brass to suit.

Ideally but I bet both will work just fine. You could always trim the long shorter and pretend you never even knew the difference.

But if its two separate lots of brass then I would keep the segregated anyways just incase there is some internal difference in dimension and it will keep you from pulling your hair out later on if you mix it all together.

 

[Robinireland]

Definitely a good idea, and one I’ve already planned for.
Beggars can’t be choosers here, so I take what’s offered and work with what I’ve got.

I was however a little surprised to notice case necks were splitting after only three firings; the first two firings were from running in the barrel with 300gr soft points (very affordable) with fairly light loads (135gr RE50) so it’s not as if I was pushing the brass to its limit.

So annealing it is then……..

 

[Taylorbok]

I should have read more carefully. Is the difference OAL only or is it in the shoulder also?

 

[Im2bent]

Was the longer brass supposed to be virgin? Perhaps its been fired a few times?

 

[Robinireland]

I’ll have to check that in the morning.

Both chamber without issues, and strike the primer just fine. I’ve primed a few of both and checked function was ok before loading any up.

Thanks for the comments.

 

[Robinireland]

Was the longer brass supposed to be virgin? Perhaps its been fired a few times?

Thanks for your comment.

Both lots were new and unfired.

The longer brass was equally pristine inside and out showing no signs of use.
It was was pre primed and had a green sealant around the edge of the primer which I believe is to ensure no moisture ingress when subjected to extreme variations in temperature. I think this brass was the run off from an ammo run for a large contract, so there was a fair bit left over.
The supplier of the long brass is 100% reliable and wouldn’t have passed fired brass on as new

 

[Geno C.]

OAL off by .010”; trim the long ones to match the short ones. Problem solved.

Necks splitting after 3 firings; annealing will help, but there is something else going on. That is the difference between loaded and fired outside neck dimensions?

 

[Robinireland]

Thanks for your comments.

0.4030” is the outside neck dimension of a loaded round (with new brass).

Unfortunately I’ve resized my fired brass, so will take the measurements of a fired case when I next book our local testing range. Wish I’d have thought of that before.

 

[Geno C.]

Measure those split ones. Splitting at the neck shoulder junction isn’t typical

 

[Robinireland]

I would if I hadn’t already resized them to make inert rounds for display.

The rifle is a Voere X5 switch barrel/calibre rifle where a barrel extension is screwed on to the threaded part of the barrel. Before torquing up the four barrel screws, you insert the bolt and close it, thus ensuring headspace is correct.
Current round count is 35 including the 10 light loads to run the barrel in (shot-clean, shot-clean, shot-clean, 2 shots-clean, 2 shots-clean, 3 shots-clean).

The split cases came from the ammo used to run the barrel in.
I’m pretty sure all five cases had two firings each (but I may be wrong).

 

[Geno C.]

Did you inspect the brass for a crease at that location prior to firing? Which batch of brass was this from, the commercial 50 or the already primed stuff?

 

[Robinireland]

The brass was from the pre primed lot, then resized and primed with CCI Magnum primers.

 

[Robinireland]

There was no sign of creasing that I’m aware of when sizing, trimming, cleaning and loading the brass.

 

[Taylorbok]

is the length difference only in the OAL or shoulder as well

 

[Robinireland]

Difference in length is OAL, as head to shoulder is the same at 2.700”

 

[Taylorbok]

Difference in length is OAL, as head to shoulder is the same at 2.700”

how does that compare to a fired case?

 

[Geno C.]

Usually excessive headspace leads to head separation, not neck splits

 

[Robinireland]

I can only measure a resized case for comparison at the moment, but they are also 2.700” give or take a thou.

My usual reloading practices with my other calibres consist of full sizing but only bumping the shoulder back just enough to allow the bolt to close without resistance from the cartridge.

 

[Robinireland]

Usually excessive headspace leads to head separation, not neck splits

Agreed.

And I’m sure Voere made absolutely sure that headspace was perfect with both the 375 and 50cal barrels.
I think my X5 was the first to reach UK shores and the factory really wanted to showcase their engineering skills, so (maybe naively) I have faith in their production tolerances.

 

[Geno C.]

I wouldn’t assume anything really. Mistakes happen. However, what you’re seeing isn’t what we usually see with excessive headspace

 

[Robinireland]

Thank you, and all who have responded with your thoughts and advice, much of which is sound.

When I book some range time at the test facility, I’ll update with further data (where relevant).

I’m definitely leaning towards annealing my brass as it’s horrendously expensive here, but more to the point, very difficult to get hold of. So investing in a good annealer will be money well spent. My 308 and 338 LM brass would benefit too.

Thanks again.